Upright cylindrical container for separating liquor and/or washing cellulosic pulp



March l, 1966 0, A, LAAKSO 3,237,773

UPRIGHT CYLINDRICAL CONTAINER FOR SEPARATING LIQUOR AND/0R WASHING CELLULOSIC PULP Filed Deo. '7, 1961 United States Patent O 3,237,773 UPRIGHT CYLNDRICAL CONTAINER FOR SEPA- RATING LIQUGR AND/ (3R WASHING CELLU- LOSlC PULP Oliver A. Laakso, Glens Falls, N Y., assigner to Aktiebolaget Kamyr, Karlstad, Sweden, a joint-stock company of Sweden Filed Dec. 7, 1961, Ser. N 157,896 Claims priority, application Sweden, Dec. 8, 1961i, 11,881/69 4 Claims. (Cl. 216-189) The present invention relates to an upright cylindrical container for separating liquor from and/or Washing cellulosic pulp which is supplied continuously or batchwise at the bottom of the container and is fed upwardly through the container.

The object of the invention is, in such a container to create a sieving device which makes it possible to sieve off liquid in counter-current to the pulp and in a distribution as even as possible over the cross-section of the container in such a manner that the sieving operation does not appreciably obstruct the feed of the pulp past the sieving device. Another object is to create a sieving device in which the tendency of clogging of the sieve apertures, and of formation on the sieve surface of a pulp layer hard to penetrate, is diminished.

The essential characterizing feature of the invention consists in the provision of a rotary sieve body carried by a shaft concentric to the container, said sieve body having an interior cavity through which said shaft communicates with an outlet `for liquid sieved off, said sieve body being essentially disc-shaped and having one or more hat and horizontal sectors which extend to the neighborhood of the Wall of the container and the radial edges of which between themselves leave one or more sector-shaped spaces, whereby the sieve body during its rotation sweeps over and sieves off liquid from essentially the entire crosssection of the container, and also allows an axially directed how of pulp up through or past the sieve body in an even distribution over the cross-section of the container. The rotation of the sieve body-which can take place with a speed having no relation of the feed of the pulp-involves that the pulp layer close to the sieve surfaces is steadily renewed and therefore is held rather loose simultaneously as the relative movement in the horizontal direction, of the sieve faces and the pulp provides selfcleaning of the sieve apertures.

The invention will be closer described hereinbelow with reference to the accompanying drawings. FIG. 1 shows two connected containers equipped with sieve devices according to the invention, one of which being shown in an elevational view and the other one being shown in a vertical sectional View which, as regards the sieve body, is taken along the line I-I in FIG. 2. FIG. 2 is a top plan View of the sieve body taken from the line lI-II in FIG. l, and FIG. 3 is a similar view of a modied. embodiment of the sieve body.

Referring to FIG. l, 11 designates an upright cylindrical container, the lower end of which merges into a conical part 13 forming a spreading hopper yfor cellulosic pulp which is supplied through a conduit 15 connected near to the point of said conical part. At its upper end the container is covered by an overhanging hood 17. Connected to the side of said hood is an obliquely downwardly directed outlet conduit 19 for pulp which in the container has been liberated from lye and/or washed. Arranged on the vertical center vline of the container is a shaft 21 which extends through stufiing boxes 23 and 25 at the point of the conical bottom 13 and at the center of the hood 17, respectively, and which is turned by a motor 27 via a gear 29. Attached to the shaft 21 approximately at the level of the merging of the conical part with the cylindrical part of the container is a double-walled sieve Vbody 31 of a design to be closer described below. The interior space 33 of said sieve body communicates through a bore 35 in the shaft 21 and a stutling box 37 outside the container with a drain conduit 39 for liquid sieved-ofl through the sieve body. Connected to the shaft 21 at a higher level of the container is one or more radially directed spray tubes 41 which through a bore 43 in the upper part of the shaft 21 and a stuthng box 45 at the upper end of the shaft communicate with a conduit 47 for the supply of a suitable washing liquid meant to displace and replace the lye or other treating liquid which accompanies the pulp supplied through the conduit 15. The tube 41 has outlet orifices which are suitably distributed for spreading the supplied washing liquid uniformly over the cross-section of the container when the shaft 21 rotates. Attached to the shaft 21 is also a rotary discharging device 4:8 consisting of radial arms having obliquely set scraper blades which act upon the upper face of the pulp column rising at the top of the container and which gradually move the pulp down into the outlet 19. Attached to the hood 17 is an annular spray tube 49 which via a valve 51 is connected to a conduit S3 carrying clean water. Said valve 51 is so constructed that the conduit 53 can be connected also to the conduit 47, in order, when desired, to supply thereto clean water, replacing or increasing the wash water quantity supplied by the conduit 83 to the spray tube 41. Attached to the rotary shaft 21 are stirring rods 55, 57 located below and above the sieve body 31.

In the embodiments of FIGS. 1 and 2 the sieve body consists of two double-walled disc sectors 59, 61 each of a center angle of about separated iby sector-shaped spaces 63, 65 each also of an angle of about 90. The disc sectors are located truly in a horizontal plane, whereby they can easily be turned in the pulp without exerting any feeding action upon the same. The edges of the sectors are preferably radial essentially along their entire lengths but close to the shaft 21 they may merge into each other along a rounded curve. The upper wall of the disc sector is foraminous and has a number of close sieve apertures, whereas the lower wall is solid. The arcuate outer edges of the sectors are situated close to the wall of the container. When the sieve body turns, the entire crosssection of the container is swept over there-by, so that the sieving action will take place uniformly at the various radial distances from the center shaft. The sector shape of the sieve body assures a correct distribution of the sieve apertures. In order to increase the size of the sieve face there is provided a number of concentric ridges 67, 69 having perforation apertures and projecting from the upper side of the sectors. The surfaces of these ridges thus `form a part of the continuous sieve face of the sieve body. As shown said ridges may be of a triangular or rectangular cross-section but, if desired, they may be replaced by proiections of some other shape. The ridges 67, 69 as shown in FIGS. l and 2 are gpreferably of generally circular configuration, thus forming bridges extending across the open space defined by sectors 63, 65 of the container cross-section. In this case the sieve body can be said to consist of a combination of fiat sectorshaped sieve discs and concentric sieve rings.

In the modied embodiment of FIG. 3 the sieve body consists of a single disc sector having a center angle of approximately 240. Projecting from the perforated upper side of the disc are concentric ridges which increase the sieve face and which in this case extend merely over the same center angle as the disc sector, thus leaving the space of located between its radial edges completely free. According to a further modification, the sieve body may consist of three or still more disc sectors separated by as many sector-shaped spaces. The total angle taken up by the spaces may be less than, but should be at least 25 percent of, the total center angle taken up by the disc sector.

The second container 11 is made identical to the first container 11 described above.

The containers are alternately connectible to the various conduits for supplied and discharged pulp, sieved-off liquid and supplied wash water. Thus the conduit 71 which is assumed to supply pulp from a continuous cellulose digester, by means of a 3-way valve 73 can be connected either to the pulp supply conduit 15 connected to the container 11, or to a corresponding conduit 15' connected to the container 11. Similarly the conduit 75 which preferably leads to a plant for recovery of chemicals, is connectible by the 3-way valve 77 either to the conduit 39 or to the conduit 39'. The pulp outlets 19 and 19' of the two containers are connected in common to a pressing device 79 where the discharged washed pulp is concentrated. The diluted wash water pressed-olf in said device is pumped by means of the pump 81 into a conduit 83 in order to be returned to the spray tubes 41. A 3- way valve 85 connects the conduit 83 either to the conduit 47 or to the conduit 47. In the same manner the clean water supplied through the. conduit 87 can be directed by means of the valve 89 either to the conduit 53 or 53'.

Due to said connection the two containers can be used for periodic and alternate lye extraction and/ or washing` of the pulp continuously supplied through the conduit 71. In each container there alternately takes place the same two steps, viz. washing and feeding, but with a mutual time dilference so that when washing takes place in one container, feeding takes place in the other, and vice versa. When the 3-way valves 73, 77, 85, 89 takes the positions shown in FIG. 1, washing takes place in the left-hand container 11. Then the conduit 15 is shut off and the pulp in the container 11 is at rest. Wash water is ejected through the stationary spray tube 49 and also through the rotary spray tube 41. The shaft 21 is turned so that the wash water supplied through the last-mentioned spray tube is evenly distributed over the crosssection of the container. The treating liquid accompanying the pulp is separated-off through the sieve body 31 and is let out through the conduit 39'. The quantity thereof essentially corresponds to the quantity of spray water supplied, and therefore the consistency of the pulp is not changed during its passage through the wash container. The sieve body is held in a steady rotation and therefore the sieving action by the disc sectors 59, 61 is shifted all around and is distributed evenly over the cross-section of the container. The result thereof is that washing liquid will move downwardly in the container with a motion directed essentially axially and will displace the lye or other treating liquid contained in the pulp and push the same before itself into and out through the sieve body. Before the border layer between washing liquid and treating liquid has reached down to the sieve body 31, the washing operation is interrupted by shifting of the said 3-way valves. This can take place automatically and by control of a central controlling apparatus 91. As regards the container 11, then there follows a feeding period without washing. Pulp is fed through the conduit 15 and is spread in the hopper-shaped container part 13 over the cross-section and passes through the open sectors 63, 65 upwardly past the sieve body 31. The latter is still held in rotation and pulp is therefore pushed upwardly at sectors of the cross-section of shifting positions so that the distribution of pulp gets uniform over the entire cross-section. At the upper end of the container the discharging device 48 acts against the rising pulp column and scrapes the pulp down into the outlet 19. The spray water conduits 47, 53 are shut oif, and the wash water extracted from the pulp in the press device 79 is led through the conduit 47 to the right-hand container 11. Also the conduit 39 is shut off during the feeding period of the container 11.

If by some reason one of the containers needs to be taken out of operation, the other container can in the meantime be driven continuously, so that washing takes place therein simultaneously with a steady even feed of pulp. Then all of said valves 73, 75, 85, 89 must be open towards the container used. If desired, the containers 11, 11 may be connected directly in parallel, so that either one performs a continuous washing of half of the pulp quantity supplied through the conduit 71.

Within this scope of the invention set forth in the following claims, the above described embodiment may be modified as to its details. For instance, the sieve body may be provided with sieve apertures even on the lower side and, in order to increase the sieve surface said lower side may also be provided with concentric ridges which preferably lie at the same radial distances as the ridges of the upper side and which form together therewith concentric sieve rings extending `all around the circumference.

I claim:

1. An upright cylindrical container for uniform extraction of liquid from a moving column of cellulosic pulp comprising means for supplying pulp to the lower end of said container, means for discharging pulp from the upper end of said container, a rotary shaft extending coaxially into the container, means for rotating said shaft, a sieve body of substantially disc-shaped transverse configuration attached to said shaft in generally perpendicular relationship thereto, said sieve body having a peripheral edge adjacent the wall of said container and radial edges extending from said Shaft to the ends of the peripheral edge, said radial edges defining a substantially sector-shaped space allowing axial flow of pulp past said sieve body during rotation of said sieve body, said sieve body having two surfaces defining an interior chamber, at least the upper surface of said interior chamber is apertured for receiving liquid into said chamber, and passage means in said shaft communicating with said sieve body chamber to provide an outlet for liquid drawn olf through said sieve body.

2. The container according to claim 1 including at least one radially projecting hollow arm attached to said shaft and having outlet apertures for washing liquid.

3. The container according to claim 2 further comprising a second passage means in said shaft communicating with said hollow arm for passage of the washing liquid into said container.

4. The container according to claim 1 wherein the apertured surface of said sieve body having at least one annular sieve ring located thereon, said sieve ring being concentric to said shaft and extending across said sectorshaped space, said sieve ring communicating with said sieve body chamber to provide additional surfaces for extracting liquid.

References Cited by the Examiner UNITED STATES PATENTS 1,820,994 9/1931 Wallin 162-42 X 2,278,453 4/ 1942 Kracklauer 210-340 2,712,488 7/1955 Brax et al. 8-156 2,878,116 3/1959 Carlsmith et al. 202-1 19 X 3,061,007 10/1962 Rich 162-237 FOREIGN PATENTS 122,608 8/ 1948 Sweden.

REUBEN FRIEDMAN, Primary Examiner.

HERBERT L. MARTIN, Examiner. 

1. AN UPRIGHT CYLINDRICAL CONTAINER FOR UNIFORM EXTRACTION OF LIQUID FROM A MOVING COLUMN OF CELLULOSIC PULP COMPRISING MEANS FOR SUPPLYING PULP TO THE LOWER END OF SAID CONTAINER, MEANS FOR DISCHARGING PULP FROM THE UPPER END OF SAID CONTAINER, A ROTARY SHAFT EXTENDING COAXIALLY INTO THE CONTAINER, MEANS FOR ROTATING SAID SHAFT, A SIEVE BODY OF SUBSTANTIALLY DISC-SHAPED TRANSVERSE CONFIGURATION ATTACHED TO SAID SHAFT IN GENERALLY PERPENDICULAR RELATIONSHIP THERETO, SAID SIEVE BODY HAVING A PERIPHERAL EDGE ADJACENT THE WALL OF SAID CONTAINER AND RADIAL EDGES EXTENDING FROM SAID SHAFT TO THE ENDS OF THE PERIPHERAL EDGE, SAID RADIAL EDGES DEFINING A SUBSTANTIALLY SECTOR-SHAPED SPACE ALLOWING AXIAL FLOW OF PULP PAST SAID SIEVE BODY DURING ROTATION OF SAID SIEVE BODY, SAID SEIVE BODY HAVING TWO SURFACES DEFINING AN INTERIOR CHAMBER, AT LEAST THE UPPER SURFACE OF SAID INTERIOR CHAMBER IS APERTURED FOR RECEIVING LIQUID INTO SAID CHAMBER, AND PASSAGE MEANS IN SAID SHAFT COMMUNICATING WITH SAID SIEVE BODY CHAMBER TO PROVIDE AN OUTLET FOR LIQUID DRAWN OFF THROUGH SAID SIEVE BODY. 